The levels of carotenoids and carotenoid esters in pumpkin (C. maxima) slices as affected by hot air drying (60-100 °C, 6-17 h) were assessed via an HPLC-MS/MS method. Among the 25 carotenoids and carotenoid esters identified in pumpkin flesh, xanthophyll diesters (including (all-E)-violaxanthin dipalmitate, lutein 3-O-myristate-3'-O-laurate, lutein 3-O-palmitate-3'-O-laurate, lutein 3-O-myristate-3'-O-palmitate, lutein 3-O-stearate-3'-O-myristate and lutein 3-O-stearate-3'-O-palmitate) accounted for 43% of the total carotenoids (853.6 ± 18.5 μg/g, dried weight). Dihydroxy xanthophylls, especially those containing 5,6-epoxy group, were more heat-labile than carotenes, while xanthophylls were less heat stable than their diester counterparts. The degradation rates (first-order reactions, R2 = 0.983-0.992) for lutein diesters (rate constant: 0.002-0.049 h-1) in pumpkin slices were only 10-20% of that for lutein (rate constant: 0.020-0.243 h-1) during hot air drying, and 76-98% of lutein diesters could be retained in the final dried products.
Keywords: Carotene; Dehydration; Heat; Lutein; Vegetable; Xanthophyll.
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